Vaccination for the treatment of cancer is critically dependent on the immune responsiveness of the patients immunized and the design of the vaccine delivered to those patients. Two patient cohorts that have not been extensively studied for vaccine responsiveness are stage llb and Illa NSCLC patients following surgery with no adjuvant therapy, and stage III colon cancer patients, with standard adjuvant therapy (5-FU-based) following surgery. Despite surgical resection to no-evidence-of-disease (NED) status and relatively good performance characteristics, these patients remain at high risk for cancer recurrence. We hypothesize that these patients will be highly responsive to immunization against tumor associated-antigens (TAA), providing an opportunity to utilize adjuvant immunotherapy to delay or prevent disease recurrence. A cancer vaccine that simultaneously delivers nine wild-type, fixed-anchor analog and heteroclitic analog HLA-A2 supertype epitopes and a pan-DR helper T cell epitope as synthetic peptides in a well-characterized adjuvant emulsion will be used to immunize these two patient populations. The primary and secondary endpoints of these clinical studies are safety and immunogenicity, respectively. We hypothesize that multiple cytotoxic T cell (CTL) responses can be induced by vaccination, and that novel analog epitopes enhanced for either HLA binding or TCR signaling will be effective immunogens for breaking immunological tolerance. The immunological studies comprising the specific aims of this proposal are: 1) Define the immune responsiveness of stage llb/Illa NSCLC and stage III colon cancer patients immunized with a multi-epitope peptide vaccine containing wild-type, fixed-anchor analog and heteroclitic analog epitopes; 2) Evaluate the specificity and avidity of T-cell responses induced by wildtype, fixed-anchor analog and heteroclitic analog epitopes; 3) Define the helper T-cell (HTL) responses induced by a pan-DR helper epitope, and determine the correlation with CTL responsiveness. These immunological studies will address several fundamental questions regarding cancer vaccinology, and in combination with safety data obtained in these clinical studies will guide consideration of this vaccine for additional Phase I studies or for Phase II testing as an adjuvant therapy for NSCLC and colon cancer.